OF THE PHYTOZOA. HI 



Sect. II.— OF THE PHYTOZOA. 

 (Plates XVIII. XIX. XX. and XXVI.) 



The Beings included under this Name : theik General Character. — 

 Division into Groups or Tribes. — The collection of microscopic beings we 

 would comprehend under the tenn Phttozoa comprises most of the Anentera 

 of Ehrenberg, with the exception of AmoehcBa, Arcellina, Dinohryhui, Bacil- 

 laria, Chstetnna, Perklinicea, and Cyclidina. After excluding these famihes, 

 there remain Monadhm, Cryptomonadina, Hydromorhut, Vohocina, Vibri^ 

 onia, and Astaskea, which, although they exhibit great diversity among 

 themselves, nevertheless have certain characters in common, whilst their 

 mutual differences in essential particulars of organization and vital endow- 

 ments are less than those separating them from the ciliated animalcules. On 

 the other hand, they— at least the majority — exhibit very marked genuine 

 affinities ^^ith the Diatome^ and Desmidie^ as plants. In point of fact, 

 these organisms stand on the confines between the animal and vegetable 

 kingdoms, — some genera distinctly belonging to the latter, others doubtfully 

 to the former, whilst many pass through such phases of existence that at 

 one time they assume the characters of animals, at another those of plants. 



This apparently mixed animal and vegetable natui'e is expressed by the 

 term Phytozoa, derived from two Greek words, signifying plant-animals. 

 Another term, used by Perty, viz. Phytozoida, is a simple expansion of the 

 word Phytozoa, signifying literally Simmsil-liJce plants. Cohn employs in its 

 stead the term Flagellata, derived from the locomotive organ or flagellum 

 which most species possess, whilst others prefer the word FJaheUifera. 



In the opinion of the majority of modem wiiters, the Phytozoa are in 

 general undistinguishable fi'om imicellular Algse, among the different families 

 of which they consequently seek to distribute them ; and doubtless the 

 creation of such a group is pui^ely artificial, and cannot be admitted in any 

 attempted philosophical or natural classification of microscopic organisms. 

 However, since so much uncertainty and dispute still prevail on the^ question 

 of the animal or vegetable natiu'e of very many, and since our knowledge of 

 the phases of existence of a large number is so imperfect, it is reaUy impos- 

 sible to estabhsh any satisfactoiy classification. On this account, and also to 

 bring together for convenience' sake a mass of information respecting several 

 collections of beings enumerated among the Anenterous Polygastrica of 

 Ehrenberg, difficult or impossible to arrange imder any other heading, we 

 resort to this artificial division, and in so doing have the example of Perty 

 and other wiiters. After describing what can be predicated of the Phytozoa 

 in general, we shall find it necessary to consider them under several sections 

 or tribes, by reason of the differences which prevail among them in form, 

 mode of growth, and other particulars ; and in speaking of each tribe shall 

 point out its general affinities to the others, and to any families of Infusoria 

 or of Algae. 



Figure. Coverings of Phytozoa. — The Phytozoa are of more simple 

 organization and of less varied outline than the ciliated Protozoa. In figure 

 they are commonly round, or oval, or eUiptical, and either present no processes, 



